Preparation of beta-lactones in the presence of difluorophosphate catalysts



Patented Aug. 15, 1950 r mmrmerrou or -morouss m PRESENCE OF nmw-ouornosr mm CATALYSTS 1 John- R, Caldwell; Kingsport,. '1enn.,. ass'ignorfto Eastman Kodak Company, Rochester, N.- It, a corporation-oi New Jersey No Drawing,

invention relates to a process, for preparing lactones or ri-hydroxy carboxylicacids-.- lwore specifically, this invention relates to a iprocess for preparingv lactones of p-hydroxy'caw boxylic acids which. comprises reacting: aketene with. a carbonylcontaining compound such as an aldehyde, ketone, diketone, or ketoester.v

Staudinger first 'showedthat a keto ketene such as: diphenyl. keten'e, addedL to aldehydes or ketonesto "give fi lactonesfi Ann. 384, 38-]:35 1911 and: Ann.- 380; 243 (1911 Staudinger alsoshowed the addition of diphenyl keteneto unsaturated ketones, and isolated dioleflns -from thereactionmixture. Ann. 401 263: '(l9L3)-.*,

Aldo kctenesg, on the other hand, are relatively unstable as compared with keto' ketenes and; dimerize rapidly under, ordinary conditions of temperature and. pressure, In the absence of. a"- catalyst, aldo ketenes olo. not. condense with;- can bony]- compounds but form the" dimer instead. With aldehydes, the ketene dimersreact; to; formunsaturated ketones. V See. Boese,,LUnited'-1States' Batent. 2,108,421,.datett February 15, 1938;

Kung in United States; Patent 2,356,.459',

: August 22 v 194e,. {has shown that ketene (GHa=C==O) reacts with aldehydes orketonesto give fl-lactones in; the presence 02- Eriedeh Crafts. type of catalysts I, have now found that fi-lactones can: be. pre pared by reacting; a: ketene with an aldehyde; ketone; diketone, or ketoester, hereinafter ref- Ierredv to as carbonyl-containing compounds in; the presence of certain metal-= salts of difiuorophosphoric: acidv as; catalysts. The metal; salts of difluorophosphor-ic acid; which I: employ as:

Application October 27, Serial No. 56,902

' become: apparent troni a consideration of catalysts cannot be classified; as FriedeL-Crafts I j' p 'acatalysts,uas=can the catalysts heretofore-.- employed inzthes prior art,- .as: exemplified by; the: Kung. patent: referred to: above. The catalysts of. my invention are-further distin'guishecli from those heretoforeemployed in that they permit theutilization of. at greaten'nmnber and variety ofcarbonylfcontaining:compoundsthamhas-been previously possible;

It: is, therefore; ana object: of this invention to" provide a: processfor preparing p -lacton'es-r A: further object is to provide a; process wherein" undesirable" carhonyliccondensation and cata= lys't' complexes arelargely or' entirely avoided. A still-further objectfi's' to provide. aprocess' which permits separation of a purer product without difllculty. Another obIiecti's to provide ncw cataly'sts for the-condensationnof; arketene and a car-1 bonyl containing= compound. .Qther.v ohjectsv will;

wherein-Rm represents amalkylgroup (espeoially 7 methyl, ethy isopropyl.-. n-pmpy1r n butyla iso:

general" formula whereinlRirepresents a; hydro-f gen atomor a; methyl grou following: examples anmdeseription.

The ketenes which are advantageously ploy'edi in practicing: my invention can-he repre- V sented by the followingzgeneralaformula:

- wherein Rand Bi each represents a hydrogen atom; an" alkyl group'- ti e. especially methyland ethyl groups, i e, alkyl' groups off'the formula C'nHzw-i wherein nrepresents a positive integer of from I to 2:)- or an aryl: groupiespecially a phenyl group, i; e. aCqI-Irg-roup) Although:

invention is directed primarily to a process in; volving; ketene- (CI-Iz= -*C=O)', any aldo ketene or any 'keto ketcne can heemployed. Typical aldo-ketenes include kcteue,v methyl; ketene, ethyl-r keteneyetcl Typical keto ketenesinclude diq methyl ketene, diethyl ketene,- d fhenyl 'ketene methyl phenyl ketene etcl- I Thev aldehydes whichaare advantageously em ployed in practicingsmy invention-can be repre sented by the followinggeneral iormula-r whereinRsrepresentshydrogen;, an ailiyi group (especially methyl; ethyl; se ropyig n-propyli n-butyl; isolim tyi secondary butyl and tertiary butyl groupsi-"i'. etan alkyl group of the form-u C1LH2n+1 wherein n represents apositive-integer of from l to at) an aralkyl group (especially benzyl or p-phenylethyl); andf/an aryl group (especially a monocycli'carylgroup of the benzene series, e. g. phenyl, m-tolyl and p-tolyl). My new process is especially useful for the preparation o'i'fl-lactorie's. from aldefiydesof the aho The ketones' which are advantageously" em--':.

played in practicing m invention can be rep resented'bythe following general rormmar v f hutyl secondary butyliand tertiary butyt groups i, e. -,analky 3 cup: ot the formula Cums?- wherein' n repr V nts-a'posltive-integer of' from The diketones which are advantageously em ployed in practicing my invention can be repre I dehyde,-l etone, ;d iketone or keto carboxylic ester, p; 1''; and which is relatively inert to the reactants.

V o Suitable solvents include the dialkyl ethers which sented by the following general formula:

wherein R5 and Rs each represents an alkyl group especiallya methyl, an: ethyl-For 'a-n-propyl group) and 112 represents a positive integer of from 11203., i

The ke'tocarboxylic 'esters -w-hich are advantageously. employed .in practicing my invention can be represented by the following general formula:

o o si timm m j-l -om or an aralkyl 4 Larger or smaller concentrations can, of course, be utilized, although there is ordinarily no advantage in doing so.

Where the carbonyl compound employed is an aldehyde, it is advantageous ordinarily to add the ketene and the aldehyde; simultaneously and in equimolecular pro-portions to the catalyst or to a .medium containing the catalyst. Where the carbonyl compound. employed is a ketone, diketone o'r-a' keto'carboxylic ester, the ketene is ordinarily advantageously added to the ketone or keto carboxylic ester containing the catalyst.

Advantageously' my new process is carried out in a solvent for the reactants, i. e. an organic liquid which dissolvesboth the ketene and the alare liquid'at 10 C., e. g.;, diethyl ether, ethyl isopropyl ether, diisopropyl ether, ethyl n-butyl ethe'i'jmethyl'n-propyl etherfetc cyclic ethers which are liquid at 10 C., e. g. 1,4 dioxane, chlorinated hydrocarbons which are liquidat 10 C., e. g. chloroform, carbon tetrachloride, ,ethylidene dichloride, ethylene dich1oride,- etc., hydrocarbons which are liquid at 10 C., e.-- g. benzene toluene,etc. 7

. In the case-"of the'lower ald'ehydes, such-as formaldehyde and acetaldehyde, ketones which are liq-uid at 10 C. can be employed as solvents because formaldehyde and acetaldehyde react withthe ketenes much faster than do the ketones to give B-lactones in accordance with my process.

I, Acetone andmethylethyl ketene-are advantaacetaldehyde, propionaldehyde, n-butyraldehyde,

isobutyraldehyde, phenylacetaldehyde, ben'zaldehyde, p methylbenzaldehyde, -cr o'tonald ehyde, furfuraldehyde, acetone, ethyl methyl ketone; methyl n-pro'pyl ketoneQmethylisopropyl ketone,

methyl n-butylketone, methyl isobutyl ket'one, diethyl ketone, methyl is'o'prope'nyl ketone, aceto' wherein M represents", divalent metal selected from the group' consistinggof'zinc, c0balt,' lead; ferrous iron and sodiumZThesemjetal salts can conveniently bepreparedf by reacting the appro-' priate metal oxide. with. 1difiuorophosphoric acid in the presenceof a loweraliph'atic alcohol, e, g. methanol, ethanol, etc. The amount of catalyst can be varied depending pn the type and reactivity of the carbonyl coritaining compound used. Generally concentrationsof, catalyst from 0.01 to 2.0 per cent by weight, basdon the weight of the carbonyl-containing compound, 'canpe employed. Goncentrations varyin "from 0.1"to 0.5 per centbyweight, based on thewei'ght "o'fthe carbonyl-cofi-' tainingcompound, have benioun'd to be es-" geously employed as solvents Whenformaldehyde or acetaldehyde is employed.

. The fi-lactones themselves are excellent solvents in which to carry out my new process and tion of Hugh J. I-Iagemeyer,- -Jr., and D'elmar'Cz Cooper, Seria1-No.'630;286, filed on April's, 1946 nowPatent No. 2,409,690 iss'ued' May- 10,- 1949.); Where ketene (CH2=C=O) is prepared by the catalytic pyrolysis of acetic acid at-reduced pres-;

sures, it is advantageous to carry out the process at reduced pressure in a scrubber-type reactor,

e. g. ketene and formaldehyde can be reacted at reduced. pressure .in a. scrubber-type reactor (in the manner describedin the :copending application of Herbert G. Stone, SerialNo. 660,285, filed on April 6, 1946,.now Patent No. 2,469,704issued May 10, 1949, which .uses.fi-propionolactone. as a solvent and boric acid as a catalyst). Many of the ,B-lactonescan be distilled from the reaction mixtures und er reduced pressures. However, many of the p-lactones dcrived'from' aldehydes and ke ones containing olefinic bonds g.- .-.C0 a hy c met ylisopr pcnyl ketone,; ill liml hy l em) andm ny 9f thefiz c nes.

ri from ketb ilepx i es e s a dd tones cannot be distilled even under reduced pressure,

without undergoing decarboxylatiom. i.; e. loss of carbon dioxide, to, 'give unsaturated compoundsf Eventhe lower; molecular .wei'ghfB-lactones derived from lower molecular weight aldehydes and.

ketones, e.; g. fer naldehyd e, acetaldehyde, ace

* tone and ethyl'inethyl-lietonahave aten'dency to ly under a low vacuum, the pump producing the vacuum having a capacity greater than the volume of vapor in the still) the reaction mixture and then to purify further the p-lactone by fractional redistillation under reduced pressure.

If desired, the fi-lactoneneed not be separated from the reaction mixture directly, but may be hydrolyzed to the hydroxy carboxylic acid which may subseq entlyhe dehydra ed to the unsatu rated vcarhw ylic said accordin to the iQllQWiQE flllafiqflfi T s eeeos Example I .-Lactone of fl-hydroaypropionic acid (p propimzolactonc).

Gaseous ketene preparegshy the pyrolysis of acetone with an electrically heated, Nichrome coil. The vapors evolved from the pyrolysis tube were cooled, and anyxunreacted acetone condensed.

Gaseous formaldehyde was prepared by heating paraforr naldehyde to a temperature ci about 13400 160? Cr I: i The gaseous keteneand gaseous formaldehyde were then mixedin substantially equimolar quantitles and passed into a stirredsolu'tion of lmg. of zinc difluorophosphate in 70 cc; of diethyf ether maintained at a temperature of from -,10

C. The heat evolved due to the exothermic nature of the reaction was removed by cooling the reaction Vessel by immersion in anice bath. The ketene and formaldehyde (both gaseous form) werecontinuouslypassed into the catalyst solution until 1.0 gram-motofeaohreactanthad been added, The catalyst was destroyedby adding-05 g. of sodiumearbonate, dis-solvedin fi cc. of water, to the reactionmixture. The superna tant liquid was separated from the precipitate 7;

which formed upqn addition oi the sodium carbonate solution. After removal of the low boiling diethyl ether, an 80 per cent yieldof -fl-pro pionolactone boiling at 37-40 6/4 mm. was obtained upon distfllationottheresidual liquid,

V .iTheialnc difiuorophosphatc used 'inthe abov example was obtained as'follows: V

. 4.1 g. of zinc. oxide were suspended infifl cc. of methanol, and 1&2 g. of difiuorophosphorioacid were slowly added with stirring. The solution was then evaporateduon-a steam bath. The salt remaining after the evaporation was complete was soluble in acetone. By substituting 'molec ularly equivalent am un s-of the-o id s of; cobalt lead, ferrous iron and cadmium for the zinc oxide, the corresponding salts of difluorophosphoric acid can be prepared,

Example II.Lactone of s-hydroxy-p-methylbutyric acid '(p-methyL-pbutyrolactone) GHa fl lr w fii ee 62 g. of'the zinc salt of dlfiuorophosphorio'acid were dissolved in 250 cc. of acetone, 'and'ketene was passed through the solution with constant stirring while, the temperature was maintained at 20%25 C. After 1 gram-mol of ketene had been reacted, the reaction mixture was 'fiashdistilled atx'80 C. and 2 mm. pressure. On redistillation of the crude distillate, fi-methyL-fi-butyrolactone boiling at 0110mm. was obtained. The lace tone was then converted to an acid as follows:

' The pure lactone was dissolved in '30 cc. of water and 30 cc. of hydrochloric acid. The solu-# tion was then distilled throu h a column, and after most of" the water had been removed, crys tals of ap-dimethylacrylic acid began to form in'the condenser. The acid was collected by ex-. tracting the aqueous distillate with diethyl ether. The yield of acid, after evaporating ofi the ether, amounted to per cent, based on the amount of ketene consumed. After recrystallization from water, the B,/8dimethyIa'crylic acid was titrated with s anda cka kali solution. Thejeeuivalent weight was fou d to he '10!) n analy s, while the ca culated, uivalent, weieht was 16d.

When a moleoularly equivalent amount of acetaldehyde and ferrous difluorophosphate replace the acetone and zinc difluorophosphate, respectively, in the-aboveexample, the lactone of fl-hydroxybutyric acid represented by the following formula: 1

and-havin a o ing poin of 54: o, at 1Q mule: mercury can be obtained.

Example III.-Lactone of p-scarbethowymethylp-hydroxybatyric acid ;.26 a, oi" cadmium chflm cphosphate (pre pa ed: according to he method descmfh d; n

ample-I) were dissplved 25 a ofie hylaceto acetate, and the solution was cooled to 15-20 C. Gaseous ketene was then passed in until a total of 84 g. had been added. The reaction mixture consisted essentially of the lactone of pcarbethoxymethyl- 9-hydroxybutyric acid represented by the above formula. The lactone was deearhoxrlated. by refluxing h reaction. mixetare a atmospheric p es ure.. :he temperature oi:

decqmneslt on e n about; S L Q C.. Onfrac'-.

m tlonalln distil ing;- he residual. ethst politeness-1e acetate (ethyl 3-methyl-3-butenoate) was obtained as a distillate boiling at 545 C./20 mm. and having a refractive index of 1.4400. On reduction-of this ester with Raney nickel at 80 C. under 1000 p. s., ethyl isovalerate was obtained. The yield of the lactone represented by the above formula was 50 per cent based on the ethyl isovalerate formed.

Example IV.Lactone of p-acetylhydrorybutyric acid 3 o H$ 2: -onro;o

Gaseous ketene.. .was passed into 86 g. of diacetyl, having dispersed therein 0.09 g. of cobalt difluorophosphate (obtained as described in Example I), until a total of 42 g. had been added. The temperature was maintained at -20 C: during the addition. The reaction mixture consisted essentially of the lactone represented by the above formula. It was then decarboxylated by heating at 90-110 C. at atmospheric pressure. When carbon dioxide gas was not involved, the residue was fractionally distilled to give isopropenyl methyl ketone boiling at 95-98 (3/735 mm., in addition to a small amount of 2,3-dimethyl-1,3-butadiene boiling at 68 (1/735 mm.

Other fl-lactones can likewise be prepared according to the process of my invention. For example, by replacin the formaldehyde of Example I by a molecularly equivalent amount of nbutyraldehyde, fi-caprolactone represented by the following formula:

Lei

can be obtained.- When 1 mol. of ketene is reacted with 1 mol. of. acetophenone in the presence of lead difiuorophosphate,, a lactone repre:

sented by the following formula:

' formula:

can be obtained. When a molecularly equivalent amount of propionyl acetone (hexane-2,4-

dione) replaces the diacetyl of Example IV, a

can be obtained. When 1 mol. of diphenylkete'ne" is reacted with 1 mol. of acetaldehyde in the presence of 0.1 per cent ferrous difiuorophosphate,a lactone-represented by'the formulazcan be obtained. Heterocyclic and unsaturated carbonyl-containing compounds can also be used to prepare fi-lactones according to the above-described process. Furfural, for]. example, produces the lactone represented by the following HC-CH H -CHCH2-C=O .9; when reacted with ketene in the presence of lead difiuorophosphate, while 'crotonaldehyde gives the lactone represented by the following formula:

The lactones produced according to the pro c-" ess of my invention are useful in the preparation of synthetic resins, polymers and rubbers. They are also valuable intermediates inthe preparation of unsaturated acids, esters, amides, and nitrlles. What I claim as my invention and desire se-' cured by Letters Patent of the United States is:

1. A process for making beta-lactones which comprises reacting at a temperature of from 50 C. to +50 C. a ketene having the formula:

C=C=O 7 R1 V wherein R and R1 each represents a member selected from the group consisting of a hydrogen atom, a methyl group, an ethyl group and a phenyl (CsH5) group with a carbonyl-containing compound selected from the group consistin of aldehydes having the formula: H

7 R2 wherein R2 represents a member selected from the group consisting of a hydrogen atom, an alkyl group having the formula CnHZn-H wherein n is a positive integer from 1 to 4, a benzyl group, a beta-phenyl ethyl group, and a phenyl (CsH5) group, ketones having the formula:

R4 wherein R3 and R4 each represents a member selected from the group consisting of alkyl groups having the formula CnH2n+l wherein n is a posi-.

tive integer from 1 to 4, a benzyl group, a betaphenyl ethyl group and a phenyl (CsI-I5) group, diketones having the formula:

o R5(OH2) m-l R0 and ketoesters having the formula:

O O ar -qomn-w -oa. M

wherein R5, Rt; R r' and"Raeach represents an alkyi group-having the formula CnHz'nH wherein is apositive integer from 1 to 4, and m repre-f sents'a, positive integer from 1 to 3, the presence of from 0.01-2.0 per centby w'eight, based on the weight of thecarbonyl-containing compound, of la catalyst selected from those repre-' sented by the following general f ormula:

wneremr/r represents a member" selected from the roup Consisting of zinc, cobalt, ferrous iron, l'eadandcadmmm; f f "2.A process for makinga beta lactone which comprises. reacting .atfatemperature of from carbonyl compound selected from the group consisting of aldehydes having the" formula:

o=o R2 wherein R2 represents a member selected from the group consisting of a hydrogen atom, an alkyl group having the formula CnI-I2n+1 wherein n is a positive integer from 1 to 4, a benzyl group,

R5 "1( Hz)... 1 tRt and ketoesters having the formula:

0 R7% (CHZ)m-I ORQ wherein R5, R6, R7 and Rs each represents an alkyl group having the formula CnHzn+1 wherein it is a positive integer from 1 to 4, and m represents a, positive integer from 1 to 3, in the presence of from 0.01-2.0 per cent by Weight, based on the weight of the carbonyl-containing compound, of a catalyst selected from those represented by the following general formula:

wherein R2 represents a member selected from the group consisting of a hydrogen atom, an alkyl group having the formula CnH2n+l wherein niis a positive integer from 1 to 4, a benzyl group,

a beta-phenyl ethyl group, and aphenyl (C'sH'5) group in the presence of from 0.01-2.0 per cent by weight, based on the weight ofthecarb'onyl' containing compound, of a catalyst selected from those represented by the" following general for mula 5 wherein M represents a member selected from the group consisting ofezinc, cobalt, ferrous iron, lead and cadmium.'

4. A process for making a beta-lactone which comprises reacting at a temperatureof from 5 ,0f o. to +5o- 'Cf. keten.e oH =ci="0) withwan alde' hyderepresentedbythe formula:

wherein R2 represents a member selected fromthe group consisting of a hydrogen atom, an alkyl group having the formula CnH2n+1 wherein n is a positive integer from 1 to 4, a benzyl group, a beta-phenyl ethyl group, and a phenyl (C6H5-) group in the presence of from 0.01-2 per cent by weight, based on the weight of the carbonylcontaining compound, of zinc difluorophosphate.

5. A process for making a beta-lactone which comprises reacting at a temperatureof from 50 C. to +50 C. ketene (CH2=C=O) with an aldehyde represented by the formula:

wherein R2 represents a member selected from the group consisting of a hydrogen atom, an alkyl group having the formula CnH2n+1 wherein n is a positive integer from 1 to 4, a benzyl group, a beta-phenyl ethyl group, and a phenyl (CcH5) group in the presence of from 0.01-2 per cent by Weight, based on the weight of the carbonyl containing compound, of cobalt difluorophosphate.

6. A process for making a beta-lactone which comprises reacting at a temperature of from -50 C. to +50 C. ketene (CH2=C=O) with an aldehyde represented by the formula:

wherein R2 represents a member selected from the group consisting of a hydrogen atom, an alkyl group having the formula CnH2n+1 wherein n is a positive integer from 1 to 4, a benzyl group, a beta-phenyl ethyl group, and a phenyl (C5Hs) group in the presence of from 0.01-2 per cent by weight, based on the weight of the carbonylcontaining compound of cadmium difluorophosphate.

7. A process for making beta-propio-nolactone comprising reacting ketene with formaldehyde at a temperature of from 50 to +50 C. in the presence of from 0.0l2.0 percent by weight, based on the weight of the formaldehyde, of a catalyst selected from those represented by the following general formula:

. x1 I whereinM represents a memberselected from the'group consisting of zinc, cobalt, ferrous iron, lead and cadmium. 5 J 1 8. Aprocess for making beta-propionolactone comprising reacting ketene'with formaldehyde at a temperature of from -50 to +50 C. in the presence of from 0.012.0 percent by weight, based on the weight of the formaldehyde, of a catalyst selected from those represented by the following general formula:

wherein M represents a member selected from the group consisting of zinc, cobalt, ferrous iron, lead andcadmium, said catalyst being dispersed in a medium consisting of beta-propionolactcne.

'9. A process for making beta-propionolactone comprising reacting ketene with formaldehydeat a temperature of from 50 to +50 C. in the presence of from (ml-2.0 percent by weight, based on the weight of the formaldehyde, of cobalt difluorop-hosph t A process for making beta-p pionolactone comprising reacting ketene .with formaldehyde.

at a temperature of from -50 to+50 C. in the presence of from 0.01-2.0 percent by weight," based on the weight of the formaldehyde, of

cadmium dlfluorophosphate.

JOHN R. CALDWELL.

' No references cited; 

11. A PROCESS FOR MAKING BETA-PROPIONOLACTONE COMPRISING REACTING KETENE WITH FORMALDEHYDE AT A TEMPERATURE OF FROM -50* TO +50*C. IN THE PRESENCE OF FROM 0.01-2.0 PERCENT BY WEIGHT, BASED ONT HE WEIGHT OF THE FORMALDEHYDE, OF CADMIUM DIFFUROPHOSPHATE. 